#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int num = 0;
	int sum = 1;
	scanf("%d", &num);
	for (int i = 1; i <= num; i++)
	{
		sum = sum * i;
	}
	printf("%d\n", sum);
	return 0;
}